How to sell your website. : If you already have established website and you want to make some money by selling it you could follow this tutorial to sell your website.
Create an account at www.Flippa.com and list your website under Sell.
Make sure your website is making decent money already
Improve your reputation and trust on Flippa.com
Keep your stats ready, like google analytics etc.
Give a decent and reasonable description, Bin price
Respond to queries and follow-up
At least keep a 7 days long bid.
Note: one key point to remember is to place your blog or website for sale only if you are convinced it is an earning business model with above average traffic.
Cheers and all the best !!